The present invention relates to the use of electrodes in catalytic processes. The main function of a catalyst is to provide a changed local structure that yields a site for a reaction to occur without the catalyst being used up itself. Catalysis gained prominence shortly after WW II as "catalytic reforming" revolutionized the petroleum industry. The literature abounds with references to catalysis applied to numerous processes.
In certain processes, the catalyst is itself an electrode. Platinum and palladium are the two most common catalytic electrodes. These are used for a wide variety of organic oxidation reactions. Titanium and carbon are also very common; titanium is used for sodium hydroxide-chlorine production; carbon is the standard catalytic electrode for fuel cells. It is to this type of process that the present invention is directed. It is well known that the total surface area and/or volume, occlusive capacity, and the local physical properties of the electrode in such a process partially determine the reaction rates. These factors can be affected drastically by the detailed preparation and maintenance of the electrodes and of the host bath of which the pH may be altered. For example, in certain reactions, milled or extruded electrodes do not function in the same manner as do cast or surface-roughened electrodes made of identical material. This can be caused by impurities that find their way into the catalytic electrode during the casting process. Moreover, the various electrochemical processes involving these catalytic electrodes can also render the electrodes less efficient as the catalytic process continues. In a lead acid battery, one electrode is lead, the other lead oxide. After a number of years in regular use, built-up of contaminants in the lead electrode renders the battery far less efficient than it would otherwise be.